comets

Celestial mechanics is a division of astronomy dealing with the motions and gravitational effects of celestial objects. The field applies principles of physics, historically Newtonian mechanics, to astronomical objects such as stars and planets. It is distinguished from astrodynamics, which is the study of the creation of artificial satellite orbits. Celestial mechanics - History of celestial mechanics. Although modern analytic celestial mechanics starts 400 years ago with Isaac Newton, prior studies addres ...

Including:

• Celestial mechanics - History of celestial mechanics
• Celestial mechanics - Ancient Civilizations
• Celestial mechanics - Claudius Ptolemy
• Celestial mechanics - Johannes Kepler
• Celestial mechanics - Isaac Newton
• Celestial mechanics - Albert Einstein
• Celestial mechanics - Open problems
• Celestial mechanics - Examples of problems
• Celestial mechanics - Perturbation theory
• Celestial mechanics - External link

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Georges-Louis Leclerc, Comte de Buffon (September 7, 1707 – April 16, 1788) was a French naturalist, mathematician, biologist, cosmologist and author. Buffon's views influenced the next two generations of naturalists, including Jean-Baptiste Lamarck and Charles Darwin. Buffon's legacy is as direct and powerful as that of his monarch, Louis XVI. Buffon is best remembered for his great work Histoire naturelle, générale et particulière (1749-1788: in 36 volumes, 8 additional volumes published after his death by Lacép� ...

Including:

• Georges-Louis Leclerc, Comte de Buffon - Wood tests
• Georges-Louis Leclerc, Comte de Buffon - Endnotes

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Astronomical spectroscopy is the technique of spectroscopy used in astronomy. As spectroscopy is described in its own article, this article focuses on its use in astronomy. The object of study is the spectrum of electromagnetic radiation, including visible light, which radiates from stars and other celestial objects. Spectroscopy can be used to derive many properties of distant stars and galaxies, such as their chemical composition and also their motion, via the Doppler shift. Astronomical spectroscopy - Stars. Including:

• Astronomical spectroscopy - Stars
• Astronomical spectroscopy - Nebulae
• Astronomical spectroscopy - Galaxies
• Astronomical spectroscopy - Quasars
• Astronomical spectroscopy - Planets and asteroids
• Astronomical spectroscopy - Comets

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In ancient times, only the Sun and Moon, a few hundred stars and the most easily visible planets had names. Over the last few hundred years, the number of identified astronomical objects has risen from hundreds to over a billion, and more are discovered every year. Astronomers need to be able to assign systematic designations to unambiguously identify all of these objects, and at the same time give names to the mo ...

Including:

• Astronomical naming conventions - Names of stars
• Astronomical naming conventions - Managing the initialisms of star catalogues
• Astronomical naming conventions - Names and boundaries of constellations
• Astronomical naming conventions - Names of galaxies
• Astronomical naming conventions - Names of planets
• Astronomical naming conventions - Natural satellites of planets
• Astronomical naming conventions - Geological and geographical features on planets and satellites
• Astronomical naming conventions - Minor planets
• Astronomical naming conventions - Comets
• Astronomical naming conventions - Designations for extra-solar planets

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The center of mass of an object is a point at which the object's mass can be assumed, for many purposes, to be concentrated. Center of mass - Example. For example, an object can balance on a point only if its center of mass is directly above the point. Alternatively, if you hang an object from a string, the object's center of mass will be directly below the string. Center of gravity, Centroid, Pappus's centroid theorem, Center of pressure Center ...

Including:

• Center of mass - Example
• Center of mass - Comparison with center of gravity
• Center of mass - Definition
• Center of mass - More formulas
• Center of mass - Aeronautical significance
• Center of mass - Motion of the center of mass
• Center of mass - Examples
• Center of mass - Barycenter
• Center of mass - Animations

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Alexis Claude Clairault (or Clairaut) (May 3, 1713 – May 17, 1765) was a French mathematician. He was born in Paris, France, where his father taught mathematics. He was a prodigy - at the age of twelve he wrote a memoir on four geometrical curves and under his father's tuition he made such rapid progress in the subject that in his thirteenth year he read before the Académie française an account of the properties of four curves which he had discovered. When only sixteen he finished a treatise on tortuous curves, Re ...

Including:

• Alexis Clairault - External link

Read more here: » Alexis Clairault: Encyclopedia - Alexis Clairault

Brian G. Marsden is a British astronomer, the longtime director of the Minor Planet Center. He specializes in celestial mechanics and astrometry, collecting data on the positions of asteroids and comets and computing their orbits, often from minimal observational information. Marsden has helped recover once-lost comets and asteroids. Some asteroid and comet discoveries of previous decades were "lost" because not enough observational data had been obtained at the time to determine a reliable enough orbit to know where to ...

Including:

• Brian G. Marsden - Honours

Read more here: » Brian G. Marsden: Encyclopedia - Brian G. Marsden

Benjamin Apthorp Gould (September 27, 1824 – November 26, 1896) was an American astronomer. He was born in Boston, Massachusetts. Having graduated at Harvard College in 1844, he studied mathematics and astronomy under C. F. Gauss at Göttingen, Germany, during which time he published approximately 20 papers on the observation and motion of comets and asteroids. He returned to America in 1848. From 1852 to 1867 he was in charge of the longitude department of the United States Coast Survey; he developed and organized the servic ...

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Astrodynamics is the study of the motion of rockets, missiles, and space vehicles, as determined from Sir Isaac Newton's laws of motion and his law of universal gravitation. It is a specific and distinct branch of celestial mechanics, which focuses more broadly on Newtonian gravitation and includes the orbital motions of artificial and natural astronomical bodies such as planets, moons, and comets. Astrodynamics is principally concerned with spacecraft trajectories, from launch to atmospheric re-entry, including all orbital maneuvers, ...

Including:

• Astrodynamics - Laws of astrodynamics
• Astrodynamics - Formulae for ellipse
• Astrodynamics - Historical approaches
• Astrodynamics - Kepler's equation
• Astrodynamics - Perturbation theory
• Astrodynamics - Modern techniques
• Astrodynamics - Conic orbits
• Astrodynamics - Transfer orbits
• Astrodynamics - The patched conic approximation
• Astrodynamics - The universal variable formulation
• Astrodynamics - Perturbations
• Astrodynamics - Non-ideal orbits
• Astrodynamics - Interplanetary superhighway and fuzzy orbits
• Astrodynamics - Reference

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Minor planets, or planetoids are minor bodies of the Solar system orbiting the Sun (or of other planetary systems orbiting other stars) that are larger than meteoroids (the largest of which might be taken to be around 10 meters or so across) but smaller than major planets (Mercury having a diameter of about 4880 km). The term minor planet is sometimes used as a synonym for asteroid though this is technically incorrect; asteroids are one group of minor planets, a category which also includes Trans-Neptunian objects and ot ...

Including:

• Minor planet - Groups out to the orbit of Earth
• Minor planet - Groups out to the orbit of Mars
• Minor planet - The main asteroid belt
• Minor planet - Families within the main asteroid belt
• Minor planet - Other groups out to the orbit of Jupiter
• Minor planet - Groups beyond the orbit of Jupiter
• Minor planet - Quasi-satellites and horseshoe objects

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Algol (β Per / Beta Persei) is a bright star in the constellation Perseus. It is one of the best known eclipsing binaries, the first such star to be discovered, and also one of the first variable stars in general to be discovered. Algol's magnitude changes regularly between 2.3 and 3.5 over a period of 2 days, 20 hours and 49 minutes. As an eclipsing binary, it is actually two stars in close orbit around one another. Because the orbital plane coincidentally matches the Earth's line of sight, the dimmer star (Algol B) passes in ...

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Alpha Centauri (α Cen / α Centauri) is the brightest star system (a triple star system) in the southern constellation of Centaurus, and contains the fourth brightest star in the night sky, with an apparent visual magnitude of −0.01. It is famous in the Southern Hemisphere as the outermost “pointer” to the Southern Cross, but it is too far south to be visible in most of the northern hemisphere. To the naked eye, the two brightest components of the system are too close for the eye to ...

Including:

• Alpha Centauri - Names
• Alpha Centauri - System components
• Alpha Centauri - Possibility of planet formation
• Alpha Centauri - Sky appearance from Alpha Centauri
• Alpha Centauri - Apparent movement
• Alpha Centauri - Alpha Centauri in fiction

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Alexis Bouvard (June 27, 1767 – June 7, 1843) was a French astronomer, born in Contamines, France. Bouvard's achievements included the discovery of eight comets and the compilation of astronomical tables of Jupiter, Saturn and Uranus. While the former two tables were eminently successful, the latter showed substantial discrepancies with subsequent observations. This led Bouvard to hypothesise the existence of an eighth planet responsible for the irregularities in Uranus' orbit. The position of Neptune was subsequently calculated, independently, by Jo ...

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Everyday ice is a crystal, which means its molecules are lined up in a repeating pattern. Amorphous ice is an amorphous solid form of water, meaning it consists of water molecules that are randomly oriented like the atoms of common glass. Amorphous ice is produced by cooling liquid water very quickly (around 1,000,000 K/s), so the molecules don't have enough time to form a crystal lattice. Just as there are many different crystalline forms of ice (about thirteen), there are also different forms of amorphous ice, distinguished p ...

Including:

• Amorphous ice - Formation techniques
• Amorphous ice - Forms
• Amorphous ice - Low-density amorphous ice
• Amorphous ice - High-density amorphous ice
• Amorphous ice - Very-high-density amorphous ice
• Amorphous ice - Hyperquenched glassy water
• Amorphous ice - Uses

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Anders Johan Lexell (December 24, 1740 – December 11, 1784 (Julian calendar: November 30)) was a Swedish-Russian astronomer and mathematician. In Russian he is known as Andrei Ivanovich Leksel (Андрей Иванович Лексель). His name is also given as Anders Johann Lexell or even Johann Anders Lexell. He emigrated to Russia in 1768. He studied the motions of comets. He computed the orbit of comet D/1770 L1 (Lexell), and it is named after him although it was discovered by Charles Messier. Th ...

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Amateur astronomy, often called back yard astronomy, is a hobby whose participants enjoy observing celestial objects. It is usually associated with viewing the night sky when most celestial objects and events are visible, but sometimes amateur astronomers also operate during the day for events such as sunspots and solar eclipses. Amateur astronomers often look at the sky using nothing more than their eyes, but common tools for amateur astronomy include portable telescopes and binoculars. Amateur astronomy - ...

Including:

• Amateur astronomy - Amateur astronomy and scientific research
• Amateur astronomy - Societies for amateur astronomy
• Amateur astronomy - Approaches to using amateur telescopes
• Amateur astronomy - Star hopping
• Amateur astronomy - GOTO telescopes
• Amateur astronomy - Comparing methodologies
• Amateur astronomy - Additional tools and activities
• Amateur astronomy - Beginning in amateur astronomy
• Amateur astronomy - Beginning with a GOTO telescope
• Amateur astronomy - Becoming acquainted with the night sky
• Amateur astronomy - Suggested reading

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Sir Wilhelm Friedrich Herschel, FRS (Hanover, November 15, 1738 – August 25, 1822 Slough, then in Buckinghamshire now in Berkshire) was a German-born British astronomer and composer who became famous for discovering the planet Uranus, and made many other astronomical discoveries. William Herschel - Biography. As Friedrich Wilhelm Herschel in Hanover, Germany, one of ten children (of which four died very young). In 1755 the Hanoverian Guards regiment in whose band William and his brother Jacob were ...

Including:

• William Herschel - Biography
• William Herschel - Other astronomical work
• William Herschel - Discovery of infrared radiation
• William Herschel - Named after Herschel

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Water has the chemical formula H2O, meaning that one molecule of water is composed of two hydrogen atoms and one oxygen atom. It is in dynamic equilibrium between the liquid and solid states at standard temperature and pressure. At room temperature, it is a nearly colorless, tasteless, and odorless liquid. It is often referred to in the sciences as the universal solvent and the only pure substance found naturally in all three states of matter. Water molecule - Forms of water. See ...

Including:

• Water molecule - Forms of water
• Water molecule - A common substance
• Water molecule - Water in the Universe
• Water molecule - Water on Earth
• Water molecule - Water in industry
• Water molecule - Physics and chemistry of water
• Water molecule - Density of water and ice
• Water molecule - Density of saltwater and ice
• Water molecule - Triple point
• Water molecule - Mpemba effect
• Water molecule - Hot ice
• Water molecule - Surface tension
• Water molecule - Electrical properties
• Water molecule - Dipolar nature of water
• Water molecule - Water as a solvent
• Water molecule - Amphoteric nature of water
• Water molecule - Acidity in nature
• Water molecule - Hydrogen bonding in water
• Water molecule - Quantum properties of Molecular Water
• Water molecule - History
• Water molecule - Systematic nomenclature and humor

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Water vapor or water vapour, also aqueous vapour, is the gas phase of water. On the Earth, water vapor is one state of the water cycle within the hydrosphere. Water vapor can be produced from the evaporation of liquid water or from the sublimation of ice. Under normal atmospheric conditions, water vapor is continuously evaporating and condensing. Normally, water vapor is invisible to the naked eye. Water vapor - General properties of water vapor. Water vapor - Evaporation/sublim ...

Including:

• Water vapor - General properties of water vapor
• Water vapor - Evaporation/sublimation
• Water vapor - Condensation
• Water vapor - General Discussion
• Water vapor - Water vapor in Earth's atmosphere
• Water vapor - Radar and satellite imaging
• Water vapor - Lightning generation
• Water vapor - Extraterrestrial water vapor

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A coronagraph is a telescopic attachment designed specifically to block out the harsh, direct light from a star, so that nearby objects can be resolved without burning out the telescope's optics. The name comes from the fact that the first coronagraphs were used to image the corona of the sun. Coronagraphs are useful for imaging coronas, near-solar comets, and even extrasolar planets. The coronagraph was introduced in 1930 by the astronomer Bernard Lyot. Since then, missions such as NASA-ESA's SOHO, SPARTAN, and Skylab have used coronagraphs to study the sun. A coronagraph concept is currently being studie ...

Including:

• Coronagraph - Other example images
• Coronagraph - Nulling Coronagraph
• Coronagraph - Optical Vortex Coronagraph

Read more here: » Coronagraph: Encyclopedia - Coronagraph